Refrigerating apparatus and method



T. B. SL .ATE

' REFRIGERATING APPARATUS AND METHOD vOriginal Filedept. 27, 1924.

i I IH INQENTOR Thomas Sla/ie Y six March 17, 1931-.

S s S n s March 17,-1931. T. B. sLATE 1,796,909

REFRIGERATING APPARATUS AND METHOD original Filed sept. 27, 1924sheets-sheet 2 INVENTOR Thomas 27.457056 35 container and this may be alarge balsa wood Patented Mar. 17, 1931 UNITED s TATEs PATENT OFFICETHOMAS B. SLATE, OFAGLENDALE, CALIFORNIA, ASSIGNOR, BY MESNEASSIGNMENTS,

T0 AMERICAN PATENTS DEVELOPMENT CORPORATION, OF EW YORK, N. Y., A COR-PORATIQN OF DELAWARE REFRIGERATING APPARATUS AND METHOD Originalapplication led September 27,1924, Serial No. 740,162. Divided and thisapplication led February 10, 1931.

My present invention relates to refrigeration of the type set forth inmy copending application Ser. No. 685,482, filed January 10, 1924, nowPatent No. 1,511,306, granted October 14th1924.

In said patent I have described and claimed various forms ofrefrigerators,le`ach characterized by having solidified carbon dioxideenclosed within the refrigerator and discharging gaseous refrigerant insuch a way that the gas affords insulation. lVhen discharged into therefrigerated space, it prevents mold and excludes air from the materialsthat are refrigerated, and otherwise refrigerates and preserves thesame.

My present invention'includes certain of the general features abovedescribed, butrelates more-specifically to refrigerating chambers andtothe container of solid carbon dioxide which is located in the upper partof the chamber and is adapted to be charged with frozen carbon dioxidewhich has been previously manufactured elsewhere.` This container isgasp-tight except for the provision of a high level vent' for escapeofthe gas, in this case. It results that when the container is chargedwith the frozen carbon dioxide, the heavy cold vgas evolved therefromdisplaces the airand drives it upwardso that the container becomesfilled with pure, dry

gas which protects the frozen carbon dioxide and greatly decreases itssublimation rate.

As stated in application No. 740,162, of

which this case is a division, Figs. 7 to l10 i11- clusive of Patent No.1,511,306show a single box into which all of the frozen carbon dioxideis charged. The heat absorption and direct chilling of the atmosphere islocalized at and upon this exterior surface, which thus becomes ineffect a refrigerant (source operating at predeterminedmoderatetemperatures.

notwithstanding the fact that/it is activated ,from Within by anintensely cold primary source, namely, the solid carbonedioxide. Thedown draft of the thuschilled atmosphere is correspondingly localized.The evolution of the gas and outpouring of the refrigerant gas issimilarly localized.

In Figs. 1 and 2 of said patent, the distribu- Serial No. 514,853.

tion of the cooling media in the car isimproved by dischargingtherefrigerant gas from the container at one end of the car' through apipe ,leading to the far end of the `car, and there is an advantagebecause the refrigerant gas carries a substantial part of therefrigerant values While the direct heat absorption at the containeraccounts for the use of a plurality of containers. I preferablysubdivide, multiply and elongate the container element so that thedirect heat absorption occurs in regions widely distributed throughoutthe length ofthe car. The discharge of gas is also subdivided anddistributed, but preferably to a less extent in the case of arefrigerator car, the distribution points being adjacent the dangerpoi'tof the car, namely, the central side doors through which the car isloaded. In this arrangement', the container absorption surface beingdistributed throughout a large part ofthe upper portion of the car actssomewhat like a thermostat and responds directly to changes intemperature of the atmosphere throughout'the refrigerator. Absorbingheat throughout a widely distributed region, the increase or decrease inthe amount of refrigerant gas which the container discharges isdirectlyresponsive to storage conditions throughout the car. Furthermore, Ibelieve I am-the first to discover. and utilize certain governingfactors and to apply them in an elongated container affording thedesired ldistributed refrigeration.

A railway refrigerator car with my complete preferred equipment, loadedand supplied with the thousands of pounds of solid because the otherlarge factor of refrigera-` dioxide will function for the shorter tripsubstantially the same as the many times geater charge required for thelonger trip. ore# over, by dividing the same maximum refrigerantcapacity among asuitable number of properly designed containers,suitably distributed inithe car, and leaving one or more of thecontainers uncharged, the car willbe self regulating for highertemperatures, say, around 36F. to 42 F.; or around say 47, as desired.

According to my present invention, the heat absorbing ca acity of thecontainers may be determineda most entirel b the total heat absorbedfrom the outside through the walls of the refrigerator car or chambertion, namely, heat generation by oxidizing reactions in a cargo" ofperishable products, such as dead ish or fresh (living) fruits,

' may be reduced to a minimum by relatively low temperatureand exclusionof oxygen which results when the gas is discharged'into .therefrigerated space: A mo'st desirable embodiment of my invention iswhere ,the total initial capaclty of the containers will be suiicient,when properly maintain approximately waterreezing temperatures withindesired limits, for the longest trip and the hottest weather for whichthe car is designed. My resent invention combines two kinds .ofrefrigeration, both of which may be controlled by the enclosing walls ofthe container which function in two ways; first, aste'xte'riorrefrigerant surface, absorbing heat andl establishing convectioncurrents by direct contact with atmosphere within the car and'thusyielding'as moderate, above-freezing refrigeration, a maj or portion ofthe refrigerantV value of the solid carbon dioxide; second, thewallsconduct this heat to the interior of the container, where some ofit isabsorbed by the gas, but most of it disappears as latent heat used inproducing a proportional amount of heavy refrigerant gas and this gas isutilized so as to yield the remaining part of the refrigerant value ofthe solid .as lower temperature refrigeration.

Hence, as one of my steps toward self control fovconstant temperature, Imake the container such that the rates at which heat is absorbed, by thewalls of the container and supplied to the solid carbon dioxide aslatent heat for volatilizing it, are practically independent ofwhetherthe container has a full charge of the solid or only arelativelyv small fraction, say, 100 pounds where a yfull charge nY(would be 1,000 pounds.` To this end, I utilize therather henomenalfact discovered by me that by ma g, or lining, the interior of theinsulated container with good conducting materiallsuch as -she'etsteelor aluminum, the solid'carbon dioxide resting upon a relatively;small area of 4the .hare-4 metal, will keep the *interior ofthecontainer at a practically conoverned, to

stant temperature, entirely around the circumfer'ence of the containerand for a wide r zone on either side. This does not mean that distantparts of the metal are maintained at approximately the same temperatureas the spot onwhich the solid rests. There is some temperature gradient,according to distance,

but where insulation'is used,'it prevents dif rect or rapid coolingand', in the preferred case, the temperature drop of over 100 F. betweenthe interior and exterior of the container is so greatthat refrigerationof the external air l(heat absorption therefrom) remains near enoughconstant for all practical purposes so long as there is some substantialamount of solid carbon dioxide left along the bottom of the container'.The practical limit "will be lowest where the solidfcarbon dioxide \doesnot contain water ice or other non- `melt1ng impuritiesv such as couldoperate toy iraise the melt-incr point; eras heat insulation,,preventing uniform heat absorption of the carbon dioxide from themetal. Obviously,

the phenomenal heat collecting quality of the metal" container is usablevfor distributing refrigerant values of thev solid to remote points,regardless `of how or whether insulationis used.

. As all the absorbed heat goes into gas mak -iiig without much changein temperature of the insulated metal lining, the lining itself becomesin e'ect ay practically constant temperature source which does notchange area during use as the frozen carbon dioxide necessarily does andhence the containers canbe designed for any desired area, without anyclose reference to `the amount of refrigerant contained therein. Thisa'ords great Moreover, the exterior transition 'surface' wheretheconvection of heat` changes to conduction seemsto be important as thecrest.

ofthe dam where the relatively uniform heat of the atmosphere in therefrigerator starts xits hundred degree drop to the temperature of theinterior of the container. Hence my invention involves desi ning" thecontainers 'to afford the desired're rigeration with only a relativelysmall normal 'temperature difference between the exterior surface of thecontainer and the refrigerator atmosphere in' which it is submerged.This may be accomsulation such that its external. surface will operateat a temperature slightly below the desired refrigerator temperature,when said surface is exposed' to air at said desired re-v frigeratortemperature., A-rough approximation for fresh fish and other productsrequiring near-freezingtemperatures, may be attained by merely makingthe insulation suchthat when exposed to ordinary moist temperature, itwill collect frost if said atmosphere is near or slightlybelow the freezing point of water, but will collect only dewv verning based on thefreezing point of water,

when said atmosphere is at temperatures ten or fifteen degrees higher.

The temperature difference and therefrigerant value per unit surfacebein thus predetermined, and, so to speakstan ardized, I

' with containers as described above' -tends tosimply provide enoughsuch surface to maintain the desired temperature for the particularrefrigerator under average conditions of its use. The insulation beingconsiderable, such area must be proportionally great and, in general, areasonable ,overestimate for the exterior surface area of the containersis an advantage because it will rovide for unusually hot weather and myot er factors of governing are controlling enough to prevent freezing incold weather.

Av refrigerator car or chamber equipped be strongly self-governing forconstant temperature notonly because of the above described greatpercentage change of temperature drop, upon slight warming or cooling ofthe atmosgihere in the refrigerator, but also because o the peculiarmode of functioning ,of the solid carbon dioxide whereby only part ofits refrigerant value is directed toward the exterior surface of thecontainer, the other. part being in the refrigerant gas that flows tothe bottom of the car and exercises its cooling e'ect on said surfaceonly in a round about wa and after considerable time has elapsed.onsequently, tlie part of the refrigerator atmosphere that is engaged insupplying the increased amount of heat to tlievcontainer does notencounter alll of the increased refrigerationiwhich it produces.

Whil these two factors are effective in op-` positionlto temperaturechange, there may be conditions where therel is a tendency to drift orshift of the ran e as a whole. In practice such drift will' e the resultof a slowly accumulating differential and I have discovered that with mylarge-area, low-dif,- ferential containers, the moisturein theatmosphere within the.y car may be utilized as the balance of powersuiicient to prevent excessive drift of temperature ran-ges and.temperature differentials. Its great effectiveness seems partly due tothe factthat by my methold the amount ofrefrigerationto be controlledisrelatively small, the heat generating reactions -in the cargo beingreduced to a minimum by low tem ratures esta'lished in the mass of thecargo y proper utilization of gas below the freezing point of water, and

vcontrol of its production by moisture functioning at and above saidfreezing point. As fish at about 25 F. and as practically allmerchandise containing freezable Water' holds it insuchform that thefreezing point is below that of water, the basic minimum temperatureallowed by this moisture control is high and effective enough for allrefrigerator purposes.

I have discovered that this moisture govcan also be relied upon forstabilizing refrigerator temperatures substantially higher than thefreezing point of water, by de-y creasing-the effective heat absorbingarea. In such cases, I prefer to use the same containers with the sameinsulationas for-fish' and other freezing pointminimum, but I employfewer of them for a like refrigerator space. Thus the refrigeratortemperature lwill have to run up to a correspondingly- .highertemperature before a balance is reached where vthere is heat lenoughabsorbed -by the reduced container area to volatilize enough refrigerantgas to maintainv the desired higher temperature, This wider temperaturedro f between the refrigerator atmosphere an container surface may notgive quite as close governing, but the governing againstfreezing is evensafer because the container frosts at high refrigerator tempera- 'turesand because the primary temperature margin of safety is greater.

The air and gas absorb and tenaciously hold certain minimum quantitiesof water down to and far below freezing and actual test seems to-provethat a relatively small remnant of it in the atmosphere of the re-rfrigerator will function as a balance wheel,

from cargo to container, while evaporation t surfaces adds an effectivelayer of insulation,

thus decreasing production of refrigerant gas, while melting of suchfrost or evaporation of dew has the opposite effect. The greater thearea. of the container surfaces relative to the volume ,of atmosphere inthe refrigerator, and the closer up to the freezing due tothenon-conducting quality of a relatively-dry gaseous atmosphere, butfevenso, I find it desirable yin certain cases to employ -water cont iners,such as shallow pans, in the bottom of the car where the temperature islowest, Afor the purpose of preventing the-atmosphereifrom becomintoovdry and-also releasing latent heat by freezing in case thetemperature falls to 32 F. for too long a period.

The significance and 'nature of the abovev 80 F. solid carbon dioxide,whether'frozen directly or made as snow and then compressed,` has aspecific gravity nearly twice that of water-ice, a cubic foot of thesolid carbon dioxide weighing somewhere'between 50 pounds and 100pounds, according to the degree of compression, and yielding about 8cubic feet ofgas per pound, measured at 32 F. Because of its lowtemperature and '"great specic gravity, such gas is nearly twice asheavy as the refrveratorairinto which itis discharged. Consequently,when it escapes from the container into the relatively still atmosphereof the refri erator chamber, it gravitates downward. T erelwill bediffusion, and if the escaping gas 'has much velocity, there will besome mechanical mixing, but even so, the initialy effect will be tobuild a poolvvof the cold carbon dioxide gasv vup from the bottom of thecar, displacing the. air and warmer carbon dioxide upwards as itrises Ihave found that there is in time estab? ,lished a tendency tostratification of the atmosphere, a relatively thin upper-layer next theroof being mostly air and noticeably warmer than the lower layers,whichare mostly carbon dioxide gas. The warm layer naturally increasesand decreases in thickness with changes in temperature, particularly in!tensity of the sunsrays on the roof, and by disposing m containers withUtheir .up er surfaces wit inthe range of/ebh and ow Y lof thicknessof'this layer, the thickening and YYin bathing contactewith greaterareas of the downward extension of the layer brings it container andthereby affords a magnified heat differential resulting in theproduction -and discharge of an increased amount ofn the refrigerantgas, which continues until retreat tire equipment for such Aa car;

of the warm layer; whether b'y discontinuance of the suns heat or as aresult of the'excess refrigeration. A

The upper warm air layer is particularly marked in refrigerator carswhere the doors do not extend to the ceiling, there is vpractically noway in which the carbon dioxide ca n force out the last seven or eightinch layer of air that lies next the roof. I prefer to vent the roof tolet itout, in which case the down spreading and retreat of' the heatwill still operate, but on a lower temperature range.

Because of the above special qualities of carbon dioxide gas and solid,my' present invention is herein described in connection with frozencarbon dioxide only, but each point of novelty of my invent-ion, asbrought out, will make evident to those skilled in the art, whether andto what extent there are now or will be ,discovered hereafter,equivalents for the carbon dioxide.

In this connection, I needl only note that` Athe nitrogen constituent ofliquid air is substantially lighter than the mixture of oxygen andnitrogen found in atmospheric an', and

that, the oxygen constituent which tends to boil off separately, afterthe nitrogen, is an active chemical agent and oxidizerwhlch 1spractically prohibited for many special reasons.

Having thus described the, important principles of my method forself-regulating refrilgeration at a relatively high temperature range bymeans of anv intense or low temperature refrigerant, I now describeapparatus whereby the various features of my method Fig. 2 1s a top planview showing the en- Fig. .3 is, avertical longitudinal section on theline 3-3 of Fig. 4, showing desirable details for the refrigerant.container shown in Figs. 1 and 2.; and

Fig. 4 is a vertical section on the line 4-v-4' of Fi 3. l

y In `igs. l to 4, I have shown my present invention ras applied to. arefrigerator car embodying my method of close temperature control for a.narrow range, particularly near `and above freezing, and particularlysomewhat below the freezing point of water, as is practically essentialfor preservation of fresh fish and many other products.

As actually used by me, thisequipment in` cludes a refrigerator car ofconventional contensely cold gas may sink and circulate beneath allparts of the cargo until diffused, moistened, warmed and then displacedupward through the cargo by fresh supplies of cold gas flowing down fromthe refrigerating devices. If the cargo is not suiiciently moist,vvvater may vbe supplied. For instance, the space below the ioormay besupplied with shallow7 tanks of Water indicated at 48, their structurebeing such that they will retain the water even under the violentbumping and. Jerklng to which such cars are subjected. If

the tanks have closed tops, freezing of the Water in the tanks or in thevatmosphere to which some of it may have' evaporated will have theeffect of releasing latent heat, preventing the temperaturefrom'gfalling much below freezing, even under trying'v weatherconditions and with the apparatus designed for normal operation atapproximately freezing point. In the case of unfrozen fish, a similarmoisture supply may be insured by packing waterice with the fish. Iftemperature rises to`around 33 Fjsuch -ice will melt slowly enough tokeep the fish in a moist condition, notwithstanding the drying effect ofthe gas. Even at times when the water in the pans 48 is frozen or whenthe water ice packed with the fish i's so cold that it does not actuallymelt, in either case,

a substantial amount of said water ice will be evaporated andabsorbed asmoisture, by anhydrous carbon dioxide gas iowing in contact therewith.Moisture furnished in any of these ways is often of advantage forpreventing o verdrying of perishable products,

independently of its function as a frost pro-- be utilized to advantagein keeping water ice from melting vuntil emergency conditions arise,when release lof its latent needed.

A refrigerator of thev above or any other desired type is supplied withcontainers of capacity, insulationk 'and surface area designedaccording-to-y principles explained eat is most above. In the `present"case", the refrigerator t space is about 40 feet long, 8 vfeet Wide and8 feet high, with the dooropenin'gs 49, about 7 feet-high by 8 feetWide, closed by doors 50. For a car of the above capacity,-I pro- Thisprovides a` `to the outside weather conditions.

`necessary large quantities of solid carbon dioxide may be stored andabsorb heat within a relatively warm, high-level, horizontally-extensiveregion o r stratum of the refrig- 'erator atmosphere; but they are evenmore vimportant because they afford a largearea horizontal supportsurface upon which the solid carbon dioxide melt's down vertically withminimum change of length and minimum change of proximity to the surfacesthrough which the heat is absorbed.

Thexupper surfaces of the containers may be arranged 7 or 8 inches belowthe roof and extend horizontally, so that the upper layer of warm air orgas will contact with greater or less area of the container according assaid layer grows thicker or thinner by great er or less heat penetratingthe roof or by' warm air or gas forced upA from below.

Four such containers whenv fully loaded will hold about 2,000 pounds to3,000 pounds of solid carbon dioxide, according as the solid is ofaverage or maximum density, which will be sufficient to. maintain atemperature' y of about 27 t o133 F. within the car for -a period of 10to 15 days or more, according On the dimensions above given, andallowing, say, 4 inches for thickness of insulation, these fourcontainers will lhave about two-fifths the capacity, but their exteriorheat absorb'- ing surface ywill be approximately the same as vfor asingle 5-foot cube balsa wood box.

The advantageV is that the heat absorbing area is distrlbuted-throughout the lengt and width of the car. Consequently, all of theconvection currents will be diffused and coming from the nearest pointsbelow the container 'and flowing drectl 0 downward again. Furthermore,the rev rigerant gas from the containers will be discharged at fourdistributed points adjacent the doors through which the car is loaded,where leaks are most likely to occurand where the containers do notextend their direct heat ab-`.

sor tion surfaces.

ese containers were made selfoverning,y preferably,- for a temperature oabout 33 F., but b my inventionthey may be designed for lower or highertemperature operation. The inner cylinder 60 may be of galvanized sheetiron, a out qlth inch thick, affording heat. conduction sufficient tokeep its entire areal at reasonablyfconstant temperature so long asthere is any substantialamount of solid remaining in the container Aalong the bottom thereof. Making the cylinfelt normally about 1 inchthick, but wrapped on and compressed by adhesive tape 62 to a thicknessof about 1/2 inch. Over this is shown a second, similar layer of hairfelt 63, held compressed b a second layer o f adhesive tape 64, and t ewhole is coveredwith alayer-of canvas or other care-- fully waterproofedfabric 65. In this case, the amount of insulation was enough so thatfrost collected thereon and evaporated therefrom in amounts varying withsmall tem- -perature changes at Jand near the freezing point of water,during normal operation with the car closed, but it all melts almostimmediately when exposed to' external atmosphere'at normal temperature,say 60 F. The cylinders may be slightly inclined so as toA beself-draining when opened and emptied. The ends of the cylinder may beclosed, and heat insulated in any desired way, as by two similarclosures, each consisting of a pair of discs 66, 67, preferaby of balsawood, each about 2 inches thick and chamfered as at 72 to affordrecesses for an annular packing 7 3 about inch to one inch in diameter,which is adapted to be wedged radiall into airtight frictionalengagement with t e cylinder 60, by forcing together the'discs 66, 67,as by means of a central bolt 69'having a head enga 'n a washer andhav-k ing a` squared shank c ose y fitting a squared recess in the disc67. The threaded portion i' 'Q'projects through the disc '66 and isprovided with a lever nut 71, provided with a handle for rotating it.Thus held, the heads can be forced out without damage, in case x ofundue'rise of internal pressure, as'by freezing of gas`outlet throughpassages 75,

75d. These passages are say 1,@ to 9/8 inch in diameter, extendingthrough the discs 66, 67,

A near the uppermost edges thereof and the gtopmost level ofthe innervent 75 drains by overiow from the v Gas within the container. "Ih'esevents may be designed for any desired )et velocity for mechanical mixingin the atmospherez but are preferably large enough to vent the interiorand prevent too great internal pressures, subject to the limitation thattheir length an'd flow resistance'should be duly proportioned withrespect to normal sublimation rate and resulting output of gas,sothat'in operation the flow will always be from t-he interior to theexterior, thereby avoiding inbreathin'gof moist air from theoutside.Otherwise, inlbreatliing air and moisture would accelerate theevaporation rate,I and th'e moisture would freeze within the container,materially increasing the heat insulation of the solid carbon dioxidethere- 4 1,79e,eoe

in and in certain cases freezing up the vent' the desired position asshown in Fig. 4, by

providing a plurality of bearing` blocks 80, each having a concave seat81 for about onehalf the cylinder circumference. The cylinder issecurely held in contact with these seats and its weight partiallysupported by straps 82 secured to the ceiling 44 by suitable bolts 83and to the sidewall 42 by bolts 84.

As the exterior lieat absorbing surface 65 will collect dew orfrostunder conditions previously described, it is desirable to preventdrip upon the merchandise being transported as by providing a sheetmetal shield or drip trough 85, which may be conveniently secured to theexterior of the straps 82 by rivets as at 86; and by securing bolts 84and screws 87.

The outlets 75, 7 5a are preferably open best possible non-conductingprotection forl the interior of the container.

In practice, water ice and frost within the container were found tobe-v'ery detrimental because it is a relatively poor conductor of heatand operates irre larly to vary the normal rate of flow ofdat from themetal to the solid carbon dioxide.. For instance,

if the solid carbon dioxide contained, or rested upon, water ice, thesolid carbon dioxide would evaporate until the mass was resting on thenon-melting water ice and the solid carbon dioxide being thus insulatedfrom contact with the metal container, would not be supplied withsufficient heat Iand would not melt fast enough. Frost an where withinor without the container wo d have the same insulating effect andwhen`melted, the y water produces the opposite effect. For this reason, thehair felt insulation was wra ped on tightly to minimize in andout breating of the moist air and was enveloped in waterproof fabric to preventwetting. A I

It will be understood that the `desirable feature of a relatively dryatmosphere in the car is not inconsistent with having it containsubstantial moisture. While my invention is independent o f theory,it isevident that if the escaping anhydrous gas flows directly ica intocontact with Water in 4"liquid form or in less degree 1n frozen form,such gas becomes more or less saturated at below zero or even belowfreezing temperatures. The fresh cold gas soon displaces the moistenedgas upward, and, at the lrelatively higher temperatures in therefrigerator atmosphere, the same or even a greater Water content, isthen insufficient to saturate it, because its saturation capacity hasbecome greater at the higher temperature. However that may be, theatmosphere deposits part of its moisture content as frost on the coldsurfaces of my containers until some sort of a steady temperaturemoisture equilibrium or condition is produced, where temperature changesat and near the freezingpoint are particularly effective for varying theheat absorption rate at said surfaces.

` This condition may be and normally is established when therefrigerator atmosphere is so far from saturated, that it tends to havea slight -drying effect on the contents and walls of the lower-part ofthe refrigerator,

but it is evident that there is a'minimum remnant of moist-ure which itis desirable to have in the car. As the atmosphere with all its,

moisture content is forced out of the car by perfectly anhydrous gas, atthe rate of a car full every two days, more or less, some supply ofmoisture is necessary but some cargoes are wet enough so that suchdrying is benei y icial rather than otherwise.

A car equipped as above and filled approximately half its height withunfrozen fish was found to be` perfectly self-regulating withinpractical limits above the freezing point of the fish throughout aten-day trip during which weather temperatures varied from belowfreezing during a snowstorm in the mountains to summer temperatures atother points of the journey. Such refrigeration may consume solid carbondioxide at an average rate of, say, 2 or 3 cubic feet per day, whichwould be about 200 to 350 ounds of dense solid. This rate of supply orefriger ant value is phenomenally small and was effective because thecold carbonl dioxide gas operated to lower temperaturend exclude oxygento a point where heat production byJ reaction within the perishableproducts was practically eliminated. The above relatively' small amountof refrigerant, yields nearly a car full of gas per day and, allowingfor the space occupied lby the packing, ,vessels and cargo, it isevident thatthe cargo was sub-k merged in carbon dioxide gas within'avery few hours and that the entire atmosphere within the car was renewedmany times during thetrip by the continuoussupply of fresh gas from thecontainers. The sameequipment will preserve the temperature for a corresondingly less time if each container is loa ed withl lessr of the solid,sa'y, three blocks each containin one cubic'foot of the solid, asindicated in ig.`2.v

On the other hand, if only three of the containers are charged, thetemperature range will be raised somewhat without much decreasing thetime the solid .will last; and if only two are charged, the rangewill beraised still furthel. 'i

As a contrast with this, it will be seen that no amount of water ice cangive temperatures around 29 F., the desirable non-freezing temperaturefor fresh sh; also that when Water ice is called upon to maintain atemperature only a degree or two above its melting point, there must bean enormous surface of theice exposed andthe air must be circulatedthereover with relatively ygreat rapidity. This entails great convectionlosses and necessitates re-icing long beforethe ice is gone, merelybecause its surface cooling area trip.

While I have shownV the insulation as uniform for the entire surface ofcontainer 52, Fig. 1, this is not an essential. For mstance,

`in Fig. 3 the disc-and-inters ace closures afford relatively smallareas aving heat absorption rates quite different from thoseof thecylindrical surfaces, while ,the exposed ends ofvbolt andsheet metal 60constitute highly-conducting, all-metal paths though their quantityeffects are small, because their exposed surface areas are such a minutefractionof the whole. Hence it will be evident `that so far as concernsthe broader aspects of myinvention, the insulationpneed not be uniformover the whole surface or evenl over any considerable portion of it.

have elected to disclose some of the important principles of myinvention in con nection with the simple apparatus lshown herein,because this apparatus was actually built and operated bv me and foundtoutilize in .greater 4or less degree, all of the novel features hereinclaimed.

For best practice of the 'temperature control features of the invention,it was found desirable to manufacture by a. separate roc-V ess, solidcarbon dioxide in the formvof b ocks' free from objectionable impuritiessuch as condensed water or lubricating oil, the blocks having dense,smooth surfaces, cylindrical in cross section, about twelve inches indiameter so as to fit the containers, and about twelve to fourteeninches long so as to .containA about :ze i

ias

. but the latter precaution is usually unnecessary. While the aboveperfections as to purity of the frozen carbon dioxide are desirable forbest practice' of my invention, it Will be I evident that the sameprinciples may be applied in the use of solidified carbon dioxide Withalmost any admixture of other liquids or materials, provided the productis standardized within limits which will permit designing apparatus tosuit the evaporating temperature and the refrigerant values of suchcomposite products. f

An im ortant commercial application of the principles of my invention isshipment of fresh fruit, vegetables, etc., from summer regions intowinter regions. In such case a car equipped for long-period, hot weatherrefrigeration may have its water containers supplied and each of itsrefrigerant containers loaded with solid carbon dioxide sufficient forthe number of days it will take the car to traverse the hot country andreach freezing temperatures. Thus loaded the solid will Y begin to failat the time the car should reach cold weather. In actual practice, thestandard refrigerator car is so heavily insulated that when oncerefrigerated to, say 27 to 33 and with sufficient carbon dioxide as inits atmosphere, the cargo will be safe or, say 48 hours, as against anoutside temperature as high as 50 F. or as low as 15 F. As againstfreezingfduring the transition period, there is the margin of 48 hoursimmunity and the water in the containers will prevent freezing ofthecargo during the remainder of the/trip. Such bodies of water will makeit practical to have a further margin of safety by' employing areasonable vover-supply of the refrigerant so that'the surface area ascompared with'its capacity and heavily insulated to preserve the samefor a long period and each derivin heat from 'and discharging theresultant coId gas into the upper part of the atmosphere containing saidproducts, the insulation of each container being predetermined withreference to the freezing point of water so as to insure relativelysmall temperature drop between said atmosphere and the heat absorbingsur-'- faces of the container when said' atmosphere is nearsaid freezingpoint.

A2. A refrigerator and a plurality of similar suitably insulatedcontainers therein for refrigeratin perishable products withoutvfreezing t em, each said container being of suitable capacity forenclos/ing cakes'of frozen carbon dioxide sulicient for a longlperiodand each derivin heat from and disc yargin the resultant col gas intothe upper part o the volume of solid in the container.

3. A refrigerator and refrigerating means therein including containermeans of storage capacity, and heat insulation -suitable forrefrigerating at moderate temperatures for long periods by means ofsolid carbon dioxide absorbing heat from and venting its refrigerant gasinto the atmosphere of said refrigerator; said container means havinglarge-area heat absorbing surfaces as compared with its capacity, inconducting relation between the solid and the atmosphere in therefrigerator,

the walls of the container including an inner surface which is of goodheat conducting m'aterial upon which the solid carbon dioxide rests andmaintains intimate contact by gravity as it melts, andan outerprotecting layer, of slowly conducting' insulating material whereby saidinner layer is maintained at approximately constant tem-perature so longas any substantial amount of the solid carbon dioxide remains in thecontainer, the amount of said insulation being considerable andpredetermined with reference to the freezing point of water so that thetemperature drop between the refrigerator atmosphere and the heatabsorbing surfaces is small when said atmosphere is near said freezingpoint, and the amount of suchsurface being proportioned for the desiredrate of refrigeration as determined lby the heat absorption rates of therefrigerator and by 'the temperatures to be maintained therein.

4. A refrigerator car in combination with means'within the car forrefrigerating'it at moderate temperatures by means of vsolid carbondioxide, said means including largecapacity highly and permanentlyinsulated containers located and shaped'so as to extend I to pointsadjacent the ends 'of the car each heat transfer walls comprising aninterior metal surface upon which thesolid carbon dioxide rests bygravity, and a permanent exterior insulating .covering for slowconduction of heat to said metalfrom the refrigerator atmosphere. y

5. A"refrigerator car or the like, in combination with means forrefrigerating it at moderate temperatures for considerable periods byrelatively large initial charges of solid carbon dioxide, said meansincluding tubular containers for said solid, of-great length as comparedwith their diameter, each absorbing 'heat and discharging the resultantgas into the car and each having walls with an interior metal surface onwhich the solid rests and an exterior insulating covering for slowconduction of heateto saidimetal from the refrigerator atmosphere, theupper heat absorbing surfaces of said containers being near butsubstantially below the ceiling of the car.

6. A refrigerator car or the like, in combination with means forrefrigerating it at moderate temperatures for considerable periods vbylarge initial charges of solid carbon dioxide, said means includingseveral large-capacity, large-area containers as compared with theirholding capacity, each having a normally open gas outlet into the carand comprising an interior metal surface and an exterior permanentheavily insulating covering for slow conduction of .heat to said metalfrom the refrigerator atmosphere, said containers being disposedhorizontally near but below the ceiling of the car.-

7. A refrigerator caror'the like, lin combination with means forrefrigerating it at moderate temperatures by means of solid carbondioxide, said means including relatively long tubular containers eachhaving a normally open gas outlet into the .car and -having wallswi`than interior metal surface and an exterior permanent heavilyinsulating covering for slow conduction of heat to said metal from therefrigerator atmosphere and arranged horizontally, lengthwise of thecar, near but not in contact with the sidewalls and ceiling thereof.

8. A refrigerator car or the like, in com` bination with means forrefrigerating it at moderate temperatures by means of solid carbondioxide, said means including tubular containers each long as comparedwith its diameter and having a normally open gas outlet passage into thecar and each container comprising an interior metal surface and anexterior permanent heavily insulating covering for slow conduction ofheatto said metal from the refrigerator atmosphere, said outlet passagesbeing of length and flow capacity adapted for continuous slowout-fiow ofgas, under normal conditions of operation; said outlet passagetraversing a i relatively large volume chamber serving as a trap againstmoisture from the exterior.

9. A refrigerator car of a type having doors `midway of the sides, incombination with means for refrigerating it at moderate temperatures bymeans of soli carbon'dioxide, said means including at least fourrelatively long tubular containers each having an interior metal surfaceand an exterior insulating covering for slow vconduction of heat fromthe exterior surface to said metal; saidcontainers being disposedlengthwise of the car, arranged two on each wside of the doorway nearbut not in contact withthe side walls and ceiling of the car, and eachhaving a removable closure and a small normally open vent discharging'at the end adjacent said doorway.

10. Agrefrigerator car of a type having doors midway of the sides, incombination with means for refrigerating it at moderate ntemperatures bymeans of solid carbon dioxide, saidmeans `including relatively longtubular containers comprising interior metal surfaces and exteriorinsulating coverings of tightly held hair felt, for slow conduction ofheat to said metal and a removable end closure, opening the full area ofthe container; said containers bein disposed lengthwise of the car nearbut be ow the ceiling thereof, with their closures presented toward themiddle of the car. Y

11. The method rbf refrigeration which consists in enclosing within achamber with the material to be refrigerated, a quantity of permanentlyand heavily insulated solid carbon dioxide which on absorption ofheatfrom the atmosphere 'within the chamber, passes directly from thesolid to the gaseous state, and permitting al1 the gas thus formed toescape intothe atmosphere of said cham-'- ber in the upper part thereof;and predetermining the temperature range of the re.

frigeration near the freezing point of water by predetermininv'theamount of active heat absorbing area of the container to the size andaverage heat absorption rate of said en,- closing chamber; and bymaintaining moisture in the atmosphere of said enclosing chamber for theformation of insulation varying frost on the containers at criticaltemperatures.

12. A refrigerator and a plurality of vpermanently insulated containerstherein lined with highly heat conductive material so that theirinternal temperature is substantially independent of the amount of solidwhich the contain, each adapted to enclose cakes of .rozenicarbondioxide sufficient for a long period', but only part of them containingthe same and each deriving heat'from and dis'- charglng the resultantcold gas lintothe refrlgerator atmosphere, the surface area ofv theinsulated containers being great as compared with their capacity, theamount of insulation of each container being correspondingly greatsothat its outer surface will collect frost from the refrigeratoratmosphere at the freezing point of water, thereby further insulatingthe container and will permit melting of such frost thereby decreasingthe insulatlon when said atmosphere is at a temperature above the rangefor which refrigeration is desired.

13.'The method of refrigeration which consists in enclosing within achamber with the material to be refrigerated a quantity of suitablyinsulated solid carbon dioxide which on absorption of heat from theatmosphere within the chamber, passes directly from the solid to thegaseous state,

rendering the rates of said heat absorption practically independent ofdecrease in the amount of sai-d rsolid-by supporting the solid upon goodconducting material, of much greater area that the solid, permanentlyand heavily insulating the heat absorbing surfaces; and controlling thetemperature range of the refrigeration by lproportioning the amount ofactive heat absorbing area of the insulation to the size and averageheat absorptio'n rate of said enclosing chamber.

14. rThe method of refrigeration which includes discharging.intenselycold, anhywhich includes limiting minimum temperatures bypermitting said gaseous refrigerant to come into heat exchangingrelation with a mass of water maintained in the refrigerated'space.

16. A refrigerator and suitably insulated containers for solid carbondioxide refrigerating partly by direct heat absorption from therefrigerator atmosphere, and partly by discharging therein the resultantcold carbon dioxide gas in combination with means ffor supporting thematerials to be refrigerated above the lowerm'ost part of therefrigerator atmosphere and means for maintaining below said support,bodies of water having large heat absorbing area. Y

17. A refrigeratoa` car or the like, in combination with means forrefrigerating it at moderate temperatures for considerableperiods bylarge initial charges of solid carbon dioxide, said means including anumber of large capacity containers each having an 1nteriormetal liningupon which the solid carbon dioxide rests and an exterior permanently,heavily insulating .covering-for slow conduction of heat from therefrigerator atmosphere to said metal; and an outlet to said atmospherefor the resultant gas, as formed, eachl container having its insulation,heat absorbing area and refrigerant storage capacity proportioned toafford its predetermined rate of refrigeration for the longest period ofrefrigeration for which the car is designed; and the aggregate number ofsuch containers being sufcient for the lowest temperature range forwhich said car is designed; whereby said car may be initially chargedforl shorter periods and the same temperatures by less of the solid ineach container; or, for higher temperatures, by charging fewercontainers.

18. The method specified by claim 14 with the further feature that theinsulation `of the Yheat absorbing surfaces and the -total area of saidsurfaces are designed to maintain refrigerator temperatureswithin a fewdegrees of the freezing point of water; that the product beinrefrigerated is fresh fish; that the fish are ept moist and moisturemaintained in the surrounding atmosphere 'by means of slowly meltingwater ice packed with the fish.

19. The method which includes refrigerating cargoes ofv products thatgenerate heat by so-called ripening or decay reactions, by enclosing ina chamber with and substantially above the level of the products, asuitably insulated supply of solid carbon dioxide refrigerating at andabove water-freezing temperatures by absorbing heat from and setting uplocal convection currents in the atmosphere above said products and alsoby liberating cold carbon dioxide gas owing down, spreading under andrisingamong said products, at temperatures and in quantities sufficientto slow said reactions to a point where the heat generation becomes apractically negligible part of heat to be refrigerated against. 7

20. The method which includes refrigerating cargoes of products thatordinarily generate heat by so-called ripening or decay re. actions, byenclosing in achamber substantially above the level of the products, asuitably insulated supply of solid carbon dioxide absorbing heat fromand setting up relatively slow atmosphere convection flow localized inthe atmosphere above said products and liberating cold carbon dioxidegas and utilizing the moisture inthe refrigerator atmosphere to controlconvection refrigeration of the upper part of said atmosphere for adesired low temperature, above the freezing point of the products, byand in accord- .ance with the freezing point of the moisture andcontrolling also the more intense refrigeration by saidarbon dioxidegas, so as to maintain approximately the same desired 1 temperaturewithin the refrigerated products.

21. The method which includes refrigerating cargoes of products thatordinarily gen-l erate heat by so-called ripening or decay reactions, byenclosing in a chamber substantially above the level of the roducts, asuitably insulated supply of solid carbon dioxide absorbing heat fromand setting up relatively slow atmospheric convection flow localized inthe atmosphere above said products and liberating cold carbon dioxidegas where it can :iow down to the bottom portion of said atmospherewithout substantial interference from said atmospheric convection; theamlounts of insulation and the heat absorbing area for the solid carbondioxide being designed for utilizing the moisture in they refrigeratoratmosphere to controlV convection refrigeration of the upper part ofsaid atmosphere for a desired low temperature, above the freezing pointof the products, lby and in accordance with the freezingpoint of themoisture and controllin also themore intense refrigeration by sai carbndioxide gas,

so as to maintain approximately the s ame desired temperature within therefrigerated products.

22. The method of operating a refrigerator car for protection of carloes of fresh fruit, vegetables, etc., against eat and cold during a tripbeginning in a Warm Weather region and ending in a freezing weatherregion, which method includes supplying the car with an initial supplyof refrigerant for the Warm weatherpart of the trip and durl ing theintermediate andlast part of said trip by permitting said gaseousrefrigerant to come into heat exchanging relation with a mass o f watermaintained in the refrigerated space.

23. The method'of operating a refri erator car for protection of cargoesof freshv ruit, vegetables, etc., during a trip involving freezing asWell as warm weather conditions, which method includes chilling thecargo and displacing tWo-thirds to four-fifths of the air by cold carbondioxide gas and during freezing weather conditions by permitting saidgaseous refrigerant to come into heat exchanging relation with a massvof water maintained in \the refrigigerjated space.

, `24. In a refrigerating system, the combination of a chamber to` berefrigerated, a

` tial insulating means,`the capacity and insu-v pluralit of containersof cakes of frozen carbon` ioxide within the chamber, each containerbein formed of or including substanlation of the containers beingproportioned to the total capacity and contents of the chamber to berefrigerated so as to effect the required amount of' refrigeration bylatent heat absorption and by the escaping carbon dioxide gas attendantuponv and resulting from the evaporation of the frozen carbon dioxidewithin said container, said containers being to said products.

located and absorbing said heat from the atmospherein a plurality ofsubstantially different regions in said chamber, for the purpos'edescribed.

25. In a refri erating system, the combination of a cham er to berefrigerated,.a lurality of containers of cakes of frozen car, ondioxide Within the chamber, each container being formed of or includingsubstantial insulating means, the capacity and insulation of thecontainers being proportioned to the total capacity and contents of thechamber to be refrigerated so as to effect the required amountofrefrigeration by latent heat absorption and b, the escaping carbondioxide evaporation o the frozen' carbon dioxide evaporation of thefrozen carbon dioxide within said container, said containers beinglocated and absorbing said heat from the atmosphere in a pluralit ofsubstantially different regions in said c amber, and discharging saidgas in regions different" from those of the heat absorption, for thepurpose described. Y

26. In a refrigeratiiig system, the combination of a. chamber to berefrigerated, which is of great length as compared with its height,

a plurality of containers of cakes of frozen carbon dioxide Within thechamber, each container bein formed of or including substantialinsulating means, tlie capacity and insulation of the containers beingproportioned to the total capacity and contents of the chamberto berefrigerated so as to effect the required amount of refrigeration bylatent heat absorption and by the escaping carbon dioxide gas attendantupon and resulting from the evaporation of the frozen carbon dioxide`said container, in combination withwater ice Cpacked with the productsto be refrigerate mosphere within said container.

29. A refrigerative method which includes evaporating solid carbondioxide "in aJ heat insulatedA chamber, by heat transfer from theatmosphere or products to be refrigerated therein; discharging gasevaporated from said solid into the atmosphere of said cliambei` andcirculating said atmospliere', including saidgas, in moisture absorbingrelation to liqui or frozen waterI and in moisture imparting relation tothe at- 30. A method of refrigeratin products that deteriorates byexposureto y carbon dioxide gas, which method includes packing saidproducts with Water ice in a heat insu-` lated chamber; producing verycold dry carbon dioxide gas from solid carbon dioxide by transferringheat thereto from the region 0i products to be refrigerated; dischargingsai( gas into the atmosphere of said chamber and circulating saidatmosphere, including said gas, in moisture absorbing said products andsaid Water ice.

31. A refrigerated chamber of greater length than width, enclosing solidcarbon dioxide containers each of greater length than Width and meansfor discharging the evaporated cold gas from said containers 'from alevel substantially above that of the Solid carbon dioxide therein; saidcontainers bein disposed lengthwise'along the walls of said chamberadjacent the top thereof.

32. A refrigerator and a plurality of solid carbon dioxide containerstherein for refrigerating perishable products, each said con- -tainerbeing of suitable capacity for enclosing a supply of rsolid carbondioxide and each absorbing heat from the upper part of the atmospherecontaining said products and means whereby the resultant cold gas isdischarged in heat exchange relation with the space or products to bererigerated,-said containers being elongated so as to be of great lengthand have great heat absorbing area as compared with their capacity. A

33. A method of reducing the amount of solid carbon dioxide required forrefrigerating products that generate heat by ripening or by decayreactions, which includes enclosing in an insulating container with theproduct, a supply of solid carbon dioxide and insulating the productsfrom the solid sufiiciently to prevent freezing of the products whileabsorbing in the solid heat derived from said products tp evaporate thesolid, at temperatures and in quantities suiflcient to prevent orsubstantially retard said heat generating reactions within the product,whereb the refrigerant values are mainly applic for absorption of heatleaking into Sald insulating container from the exterior.

Signed, at Glendale, in the county of Los Angeles, and State ofCalifornia, this 6th day of February, A. D. 1931.

THOMAS B. SLATE.

relation tc

